Rolling protective shutter assemblies or roll shutter assemblies are used to cover windows, doors or other openings of buildings and the like to provide a measure of security from damage, break-in and theft at those locations. Roll shutter assemblies typically include a frame disposed around the opening, a shutter made up of a series of interconnected or hinged slats that travel within the frame and a shutter housing that stores the shutter in a rolled-up manner. The shutter, which is typically made of metal or other hard-to-compromise material, moves within one or more guides or tracks on the frame from an open position, in which the shutter is rolled up and stored within the shutter housing, to a closed position, in which the shutter is disposed over the opening, and vice-versa. Roll shutters may also include a mechanism, such as a hand crank or a motor, that moves the shutter within the tracks from the closed or extended position to the open or retracted position. Although roll shutter assemblies provide additional protection to openings, roll shutter assemblies are not completely immune from attacks by intruders who may compromise the integrity of the roll shutter assembly using saws to cut holes in a shutter or using crowbars or other devices to pry the slats of the shutter apart, pry the shutter out of the tracks and the like.
Common methods of alarming openings involve the use of contact assemblies that have a first electrical contact placed on, for example, a window or a door, and a second electrical contact placed on a stationary frame in which the window or door is mounted so that the first and second contacts touch when the window or door is closed. In some instances, an electrical strip or conductor may also be placed around the window or door to create an electrical circuit within the window or door. Whenever the electrical circuit is broken because, for example, the window or door is opened or is broken (thereby disconnecting the first and second contacts or breaking the electrical strip), the alarm activates.
However, unlike a window or a door, the shutter of a roll shutter assembly is somewhat flexible and is designed to roll in tracks or guides which typically have large tolerances. As a result, the shutters of roll shutter assemblies do not necessarily close at the exact same spot consistently, making it difficult to establish a reliable contact between the shutter and the frame. In addition, contact alarm systems can be overly sensitive to movement of the shutter. In fact, contact assemblies may be triggered by winds blowing against the shutter, bumps or other incidental contact made by passers-by and the like. As a result, contact assemblies used in other alarming applications cause an unacceptable number of false alarms when used with roll shutter assemblies. Still further, because the shutter of a roll shutter assembly is made of metal or other bendable material, the integrity of the shutter may be compromised without actually interrupting a circuit created by an electrical strip disposed around the edge of the shutter. For example, an alarm that has a conductor placed around the outer edge of the shutter may be defeated by simply cutting a hole through the center of the shutter.
To avoid the problems of false alarms, roll shutter assemblies may be installed on the inside, as opposed to the outside, of openings. While this configuration reduces the problem of false alarms, the level of protection offered by the shutter is also reduced because an intruder can still damage a window, for example, before encountering the protective shutter assembly.